克倫特羅
Clenbuterol
1-(4-Amino-3,5-dichlorophenyl)-2-tert-butyl aminoethanol HCl
別名: Ventipulmin · Aeropulmin · Spiropent · Broncodil · Ventilan · NAB-365 · Broncoterol · Bronq-C · Cesbron · Clembumar · Clenasma · Clenbutol · Contrasmina · Contraspasmin · Monores · Novegam · Oxibron · Oxyflux · Prontovent · Ventolase
由 VetSheet 獸醫團隊審訂更新於 2026年4月5日本內容以實證獸醫文獻為本
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Bronchodilator | Initially, 0.8 micrograms/kg (practically: 0.5 mL of the commercially available syrup/100 lb. BW) twice daily for 3 days; if no improvement increase to 1.6 micrograms/kg (practically: 1 mL of the commercially available syrup/100 lb. BW) twice daily for 3 days; if no improvement increase to 2.4 micrograms/kg (practically: 1.5 mL of the commercially available syrup/100 lb. BW) twice daily for 3 days; if no improvement increase to 3.2 micrograms/kg (practically: 2 mL of the commercially available syrup/100 lb. BW) twice daily for 3 days; if no improvement discontinue therapy. | PO | q12h | Recommended duration of therapy is 30 days; then withdraw therapy and reevaluate. | 🌎 NA |
| Adjunctive treatment for dystocia emergencies | 300 micrograms per 500 kg mare IV slowly | IV | Single dose | — | 🌎 NA |
| Adjunctive treatment for dystocia emergencies | 10 mls of clenbuterol syrup orally as the mare walks in the door. | PO | Single dose | — | 🌎 NA |
- Bronchodilator: ARCI UCGFS Class 3 Drug
- Adjunctive treatment for dystocia emergencies: Parenteral formulation not available commercially in the USA. Fast onset allows quick decision if uterine relaxation will correct the problem. May be used with sedatives/analgesics; xylazine or detomidine may potentiate uterine relaxant effects.
- Adjunctive treatment for dystocia emergencies: Author's hospital protocol upon arrival of a dystocia.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
概覽
克倫特羅 (Clenbuterol) 是一種強效且長效的乙型交感神經受體致效劑 (beta-2-adrenergic agonist)，在獸醫學中主要用於馬匹，作為支氣管擴張劑以治療呼吸道阻塞疾病，例如反覆性呼吸道阻塞 (RAO)（以前稱為慢性阻塞性肺病 COPD 或「喘鳴症」）。
除了呼吸道應用外，它偶爾也被用作子宮鬆弛劑 (tocolytic)，以協助處理母馬的難產問題。
臨床關鍵要點：
- 嚴禁食用動物使用：高劑量的克倫特羅具有重新分配體內脂肪與肌肉的作用（增加肌肉、減少脂肪）。由於人類食用受污染的肉類後會產生嚴重的殘留毒性 (relay toxicity)（導致嚴重震顫、心跳過速及住院），全球皆嚴格禁止將其用於產食動物。
- 濫用潛力：由於其類似同化類固醇的作用，常在人類健美和減肥圈中被濫用。獸醫師必須警惕藥物被非法轉用的情況。
- 內分泌與心臟影響：馬匹長期使用可能導致有氧運動能力下降、心肌肥大、心肌膠原蛋白浸潤以及免疫功能改變。
作用機制
Clenbuterol selectively binds to and activates beta-2 adrenergic receptors on smooth muscle cells.
Primary Pathway:
Beta-2 Receptor Activation → Stimulates G_s proteins → Activates Adenylyl Cyclase → Increases intracellular cyclic AMP (cAMP) → Activates Protein Kinase A (PKA) → Decreases intracellular calcium concentrations → Results in smooth muscle relaxation (bronchial, vascular, and uterine).
Secondary Mechanisms:
- Anti-inflammatory Effects: Inhibits the release of pro-inflammatory cytokines (such as Interleukin-1β and Tumor Necrosis Factor-α) from pulmonary macrophages.
- Mucociliary Clearance: Increases ciliary beat frequency in the respiratory tract, enhancing the clearance of excessive mucus associated with RAO.
安全性與警告
禁忌症
- Food-producing animals (strictly banned by law)
- Horses suspected of having cardiovascular impairment
- Pregnant mares near full-term (unless used specifically for dystocia management)
不良反應
- Muscle tremors
- Sweating
- Restlessness
- Urticaria
- Tachycardia
- Creatine kinase (CK) elevations
- Ataxia (rare)
- Abortion in pregnant animals
- Cardiac hypertrophy and collagen infiltration (with chronic use)
注意事項
LEGAL WARNING: Extra-label use in food animals is strictly prohibited by federal law due to severe human toxicity risks.
- Cardiovascular Risk: Use with extreme caution in horses with preexisting cardiac disease; tachycardia is a common side effect.
- Pregnancy: Antagonizes oxytocin and prostaglandin F2alpha. Can diminish normal uterine contractility and induce abortion. Do not use in late-term pregnant mares unless specifically managing dystocia.
- Performance Horses: Designated as an ARCI Class 3 Drug. Use is prohibited or highly regulated by racing and show associations.
- Drug Diversion: Be highly alert for clients attempting to obtain this medication for illicit human use (bodybuilding/weight loss).
藥物相互作用
May predispose the patient to ventricular arrhythmias, particularly with preexisting cardiac disease.
May antagonize clenbuterol's bronchodilating and tocolytic effects.
May increase the risk of cardiac arrhythmias.
Clenbuterol may antagonize the ecbolic effects of dinoprost.
Clenbuterol may antagonize the uterine contracting effects of oxytocin.
Concomitant administration may enhance the adverse cardiovascular and neurologic effects of clenbuterol.
May potentiate the vascular effects of clenbuterol.
監測
- Clinical efficacy (improvement in respiratory rate, effort, and reduction of cough)
- Heart rate and rhythm (monitor for tachycardia or arrhythmias)
- Signs of muscle tremors, sweating, or restlessness
- Creatine kinase (CK) levels if myopathy is suspected
藥物動力學
半衰期
吸收
Peak plasma levels occur 2 hours after oral administration in horses.
分佈
Volume of distribution is approximately 1.6 L/kg after multiple oral doses.
代謝
Hepatic metabolism; specific pathways not detailed, but systemic clearance is reported as 94 mL/kg/hr.
排除
Primarily renal. Urinary concentrations are approximately 100X those found in plasma and can persist at quantifiable levels for 288 hours (12 days) after the last oral dose.
過量
Overdoses can cause severe sympathomimetic toxicity (extreme tachycardia, arrhythmias, severe muscle tremors, hypertension followed by hypotension, and hypokalemia).
Treatment:
- Decontamination: Emptying the gut (gastric lavage/activated charcoal) may be appropriate depending on the dosage and timing of ingestion.
- Medical Management: Provide supportive therapy. Administration of parenteral beta-blockers (e.g., propranolol, esmolol) may be considered to control heart rate, rhythm, and elevated blood pressure.
可用產品
劑型
- Oral Syrup
- Injection (Not commercially available in the USA)
獸醫用
- Clenbuterol HCl Oral Syrup: 72.5 micrograms/mL in 100 mL, 330 mL, 460 mL bottles (Ventipulmin Syrup, Aeropulmin Syrup)
各地核准狀態
暫無法規資料: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Store the commercially available syrup at room temperature and avoid freezing. Always replace the safety cap on the bottle securely when not in use.
飼主須知
馬主重要須知
- 用途：克倫特羅用於幫助患有呼吸道疾病（如「喘鳴症」或反覆性呼吸道阻塞）的馬匹擴張氣管。
- 副作用：在開始服藥時，您可能會注意到馬匹出汗、焦躁不安或肌肉顫抖。牠們的心跳率也可能增加。如果這些症狀嚴重或持續存在，請聯繫您的獸醫師。
- 競賽規定：許多馬術競賽和展覽協會嚴格管制或禁止使用此藥物。參賽前請務必向所屬機構確認停藥期規定。
- 人類安全警告：請將此藥物嚴格放置於兒童及未經授權者無法觸及的地方。克倫特羅有時會被人類非法用於健美或減肥，這可能導致嚴重且危及生命的心臟問題。
- 產食動物禁令：絕對不可將此藥物給予供人類食用的動物（如牛、豬、羊等）。這是違法的，且會導致食用該肉類的人類嚴重中毒。
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用，不能取代專業判斷或廠方最新藥品說明書。